Intersting COLT upper receiver feature

[masakari]

Nope, mine doesn't.

All of the 6940 series now do, though. Early ones didn't, but that was quite a few years ago.

[vicious_cb]

On a DI gun the wear from the cam pin stops after a certain point. Im not sure why it would be an issue unless you plan on going with an external piston system.

[sig1473]

Must be an early rifle. Does it have the "patent pending" stamping on the left side?

No, it has US Patent No. 7,131,228